This proposal involves an analysis of the role of cellular factors in the immune response of mice to Capillaria hepatica, a nematode whose life cycle and developmental stages are localized in the liver. An assessment will be made of the local or general nature of the recruitment of lymphoid and non-lymphoid cells appearing at the local site of infection with particular attention to the role of the egg in the formation of granulomata, since in other helminth infections these have been demonstrated to be of particular importance in hepatis granulomas. Two major areas of investigation are proposed within which several subdivisions will be considered: (1) a study of the correlation between cell mediated immunity and granuloma formation, and (2) a determination of the role and importance of immunoglobulins and the non- lymphoid cell response.